The word “turn” does seem to be used interchangeably throughout the OD&D rule books to mean different things at different times, i.e. a turn of movement in a dungeon, a turn of combat and even a turn of movement in the wilderness. This doesn’t pose much of a problem in most cases, but one example of when it does is in determining a spells duration. Many of the spells listed in Men & Magic provide a duration in turns that the effects of the spell are supposed to last, but there is no clear indication of whether each of these turns represents a 10 minute turn or so many rounds/turns of combat.

OD&D Spell Duration - How Long is a Turn?

To help unravel this problem I think it’s necessary to look at what Gary Gygax says about time in both OD&D, AD&D and CHAINMAIL so we have a basis for comparison as all three works are detailed under the same author and contain several of the same spells.

I think Gary expresses it quite clearly in the AD&D Player’s Handbook. “In adventuring below ground, a turn in the dungeon lasts 10 minutes (see also MOVEMENT). In combat, the turn is further divided into 10 melee rounds, or simply rounds. Rounds are subdivided into 10 segments, for purposes of determining initiative (q.v.) and order of attacks. Thus a turn is 10 minutes, a round 1 minute, and a segment 6 seconds. Outdoors, time is measured in days, usually subdivided into daylight (movement) and night (rest) periods. Thus, while actual time playing is about the same for a dungeon adventure, the game time spent is much greater in the case of outdoor adventures.

The parallel with OD&D is so strong that I don’t think it can be brushed off:

As in AD&D a turn in the dungeon lasts 10 minutes: “THE MOVE/TURN IN THE UNDERWORLD: Movement [...] is in segments of approximately ten minutes. Thus it takes ten minutes to move about two moves — 120 feet for a fully armoured character. Two moves constitute a turn [...] Melee is fast and furious. There are ten rounds of combat per turn.”

OD&D also tells us in regards to wilderness movement on a hex map that “Each move will constitute one day. Each day is considered a turn.”

In Eldritch Wizardry, there is the following expansion: “Alternate Combat System: (Addition) The question of when various actions take place during a melee round often arises. In order to simply and easily satisfy the problem of when any action can take place, the melee round has been further subdivided into pre-movement, movement of six segments, and post-movement, or eight parts in all.” It’s important to realise that the supplement provides two tables: one for Missile Fire and Spell Casting, which has 8 segments (including pre-movement and post-movement) and one for Movement which has only 6 segments. 

It’s difficult to establish exactly what is meant by pre-movement and post-movement but as the Movement Segment table in Eldritch Wizardry does not include these, there is a strong implication that pre and post is merely referring to either very dexterous characters potentially being able to act prior to any movement taking place, or very undexterous characters acting just after all characters have moved. I am not entirely sure but if the 8 segments are divided equally into 8 parts then a single segment lasts 7.5 seconds (slightly longer than in AD&D) but it seems that pre and post movement should not be included in this calculation, or should be significantly shorter than 7.5 seconds. If we treat them as not being part of the calculation then the round would be 10 seconds per segment. For the sake of this discussion I don’t think it matters as the point I am trying to make is that: as in AD&D, OD&D divides the 10 minute turn into 10 rounds and then further divides this into segments.

CHAINMAIL simply tells us that “one turn of play is roughly equivalent to one minute of time in battle.” This game does not consider anything other than battle with scale miniatures so there are no other considerations required other than a combat turn. The rules do mention “rounds” in regards to melee but only 1 round of melee occurs each turn as a distinct phase in the games turn order. The time this takes is not considered and remains abstract. Thus we have:

                    AD&D           OD&D           CHAINMAIL

Wilderness Turn     1 day          1 day          N/A

Dungeon Turn     10 minutes     10 minutes     N/A

Combat Turn         10 minutes     10 minutes     1 minute

Combat Round        1 minute       1 minute       N/A

Round Segment       6 seconds      10 seconds?    N/A

Here a disparity has already been highlighted between a CHAINMAIL turn and a D&D turn. This gives us a basis for comparison when looking at spell duration between the three systems and may go someway in explaining the root of the term “turn” being used to mean different things in different context. In other words “I think perhaps that as OD&D grew out of CHAINMAIL, when the list of spells was expanded the word “turn” was used in the context of a 1 minute combat turn.

The levitate spell is a good one to look at to test this theory as it appears in CHAINMAIL, OD&D and AD&D. The CHAINMAIL Levitate tells us that it is “a spell which allows the user to rise 6" per turn for up to six turns.” If we are playing CHAINMAIL then this means 6” per turn for up to 6 minutes or 6 combat rounds.

The OD&D Levitate spell has duration of “6 turns + the level of the user [...] with upwards motion at 6”/turn.” This is hardly changed, so it would seem quite reasonable to believe that in this context 6 turns is still 6 minutes or 6 combat rounds.

In AD&D if the Levitate spell “is cast upon the person of the magic user, he or she can move vertically at a rate of 20’ per round.” This is a little less than CHAINMAIL and OD&D’s 60’ (6”) per round, but only by 1/3rd. Interestingly the spell description does go on to say “If cast upon another creature, the magic-user can levitate it at a maximum vertical movement of 10’ per round” and I’ll explain the relevance of this very shortly. The AD&D version of the spell also only has a duration of “1 turn/level” or 1/6th of the time allowed by the OD&D Levitate spell.

AD&D does provide a clear explanation of what is meant by “turn” in regards to spell duration: “Duration” is given as number of turns, rounds, or simply “instantaneous”, as in the case of a lightning bolt which lasts only a brief moment.” So we can say for sure in the case of the AD&D Levitate spell that use of the word “turn” means 10 minutes. Therefore 20’ per round (as the spell describes) is the same as 200’ per turn. Much more than the OD&D’s 60’ per turn. However, if the AD&D Levitate spell is cast upon another creature instead of the magic-user then verticle movement is 10’ per round or 100’ per turn. 60’, 100’ or 200’ are not such major differences. 

If we compare the AD&D and CHAINMAIL version of the spell, the difference in duration is not a significant one.

                            AD&D           CHAINMAIL

Levitate Spell Duration     1 turn or      6 turns or

                            10 minutes     6 minutes

If we look at the OD&D version we have two options, either:

1. 6 turns = 60 minutes because a turn in duration is the same as an underworld turn, or

2. 6 turns = 6 minutes because a turn in duration is the same as a combat round

We have no logical reason to pick option number 1 because this would mean a HUGE disparity between the CHAINMAIL version of the spell and the AD&D version. Why would Gary do this?

To make this easier to conceptualise we could use the term “spell turn” in the context of spell duration, and have something like this:

                    AD&D           OD&D           CHAINMAIL

Wilderness Turn     1 day          1 day          N/A

Dungeon Turn     10 minutes     10 minutes     N/A

Combat Turn         10 minutes     10 minutes     1 minute

Combat Round        1 minute       1 minute       N/A

Round Segment       6 seconds      10 seconds?    N/A

Spell Turn          1 minute       1 minute       1 minute

If we look at all the OD&D spells comparitively presuming an OD&D “spell turn” is a minute in length and then compare them with OD&D & CHAINMAIL we can get a much clearer picture of how these things compare:

SPELL                    AD&D           OD&D           CHAINMAIL

Levitate                 1 turn or      6 turns or     6 turns or

                         10 minutes     6 minutes*     6 minutes

Slowness                 3 rounds or    3 turns or     2 turns or

                         3 minutes*     3 minutes      2 minutes

Haste                    3 rounds or    3 turns or     3 turns or

                         3 minutes*     3 minutes      3 minutes

Confusion                2 rounds or    12 turns or    1 turn or

                         2 minutes*     12 minutes     1 minute

Anti-Magic Shell         1 turn or      12 turns or    6 turns or

                         10 minutes*    12 minutes     6 minutes

* Duration is further increased by level of the magic-user.

Note that the Haste spell is almost identical in duration across the board.

Now imagine if a spell turn in OD&D lasted a full 10 minutes... There would be such a disparity with the other two systems that would be completely inexplicable.

After carrying out this little investigation I am quite happy to conclude that in regards to spell duration in OD&D 1 turn = 1 minute. However, I would love to hear your thoughts if you disagree and why. Have I overlooked something?